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Weather & Climate in Garrison, IA
Temperature, precipitation, air quality, natural hazards, and monthly weather data.
Garrison experiences four distinct seasons with an average annual temperature of 46°F (8°C). Winters average 17°F in January while summers reach 71°F in July. The area gets 260 sunny days per year, above the national average. Annual precipitation totals 37.9 inches. The area receives 33.6 inches of snow annually, a moderate snowfall amount. Air quality is rated Good with a median AQI of 43. The city sits at an elevation of 893 feet.
Temperature
17°F Jan (-8°C)
71°F Jul (22°C)
| Annual Average | 46.0°F |
| 15% below US avg | |
| January Average | 17°F (-8°C) |
| July Average | 71°F (22°C) |
| Sunny Days | 260 days/yr |
Geography
| Elevation | 893 ft (272 m) |
| Area | 0.3 sq mi (0.6 km²) |
| Population Density | 942/sq mi |
| Coordinates | 42.1450°N, 92.1442°W |
| Timezone | America/Chicago |
| County | Benton County County |
| Nearest Airport | The Eastern Iowa (CID) 28 miles away |
Precipitation & Snow
Air Quality
| AQI Median | 43.0 |
| Rating | Good |
Natural Hazard Risk
| Overall Risk | Very Low |
| Risk Score | 28.8 / 100 |
| Social Vulnerability | 10.6 / 100 |
| Community Resilience | 92.7 / 100 |
Hazard Breakdown
| Tornado | Relatively Low |
| Hurricane | Very Low |
| Earthquake | Very Low |
| Wildfire | Very Low |
| Flood | Relatively Low |
| Hail | Relatively Moderate |
| Strong Wind | Relatively Moderate |
| Heat Wave | Very Low |
| Winter Weather | Relatively Low |
| Lightning | Very Low |
| Ice Storm | Relatively Low |
| Drought | Relatively Moderate |
| Cold Wave | Very Low |
| Landslide | Very Low |
Source: FEMA National Risk Index v1.20 (Dec 2025)
Tornado History
633 tornadoes (EF0+) recorded within 100 km since 1950. Strongest on record: EF5. Total: 27 fatalities, 597 injuries.
| Date | Rating | Distance | Path | Fatalities |
| May 25, 2008 | EF5 | 75 km | 41.0 mi | 9 |
| May 15, 1968 | EF5 | 61 km | 13.1 mi | 5 |
| Mar 31, 2023 | EF4 | 93 km | 19.9 mi | 0 |
| Mar 13, 1990 | EF4 | 60 km | 19.0 mi | 0 |
| May 30, 1989 | EF4 | 86 km | 11.0 mi | 0 |
| Aug 12, 1974 | EF4 | 44 km | 2.0 mi | 0 |
| Aug 12, 1974 | EF4 | 59 km | 5.0 mi | 0 |
| Aug 26, 1965 | EF4 | 18 km | 4.7 mi | 1 |
| Sep 1, 1961 | EF4 | 100 km | 26.6 mi | 0 |
| Apr 30, 1954 | EF4 | 33 km | 80.4 mi | 0 |
| Jul 19, 2018 | EF3 | 73 km | 8.4 mi | 0 |
| May 25, 2008 | EF3 | 52 km | 32.0 mi | 0 |
| May 21, 2004 | EF3 | 29 km | 3.0 mi | 0 |
| May 11, 2000 | EF3 | 49 km | 18.6 mi | 1 |
| Jul 27, 1995 | EF3 | 63 km | 20.0 mi | 0 |
| Jun 19, 1993 | EF3 | 59 km | 9.0 mi | 0 |
| Jul 13, 1992 | EF3 | 84 km | 5.0 mi | 0 |
| Jun 28, 1990 | EF3 | 100 km | 9.0 mi | 0 |
| May 30, 1985 | EF3 | 93 km | 34.0 mi | 2 |
| Sep 16, 1978 | EF3 | 88 km | 31.8 mi | 6 |
Source: NOAA Storm Prediction Center (EF0+, 1950–2024, US only).
Wildfire History
4 wildfires (100+ acres) recorded within 100 km. Largest: UNNAMED (939 acres, 2009).
| Year | Name | Acres Burned | Distance |
| 2009 | UNNAMED | 939 | 32 km |
| 2010 | FOLEY | 786 | 33 km |
| 2011 | ACE AUTO | 676 | 36 km |
| 2011 | IRCP WUI ROFAE #2 FY11 | 510 | 32 km |
Source: NIFC/IRWIN Wildfire Records (100+ acres).
Monthly Weather
| Month | Avg Temperature | Precipitation | Summary |
|---|---|---|---|
| January | 17°F (-8°C) | 0.9 in | Coldest, Driest |
| February | 24°F (-5°C) | 1.0 in | |
| March | 36°F (2°C) | 2.2 in | |
| April | 49°F (9°C) | 3.4 in | |
| May | 61°F (16°C) | 4.1 in | |
| June | 70°F (21°C) | 4.5 in | Wettest |
| July | 71°F (22°C) | 4.1 in | |
| August | 71°F (22°C) | 4.3 in | Warmest |
| September | 63°F (17°C) | 3.9 in | |
| October | 51°F (11°C) | 2.6 in | |
| November | 36°F (2°C) | 2.1 in | |
| December | 23°F (-5°C) | 1.4 in |
Garrison has a seasonal temperature swing of 54°F / from 17°F in January to 71°F in August. Total annual precipitation is 34.5 inches, with June being the wettest month (4.5") and January the driest (0.9").